In the field of commercial art, there is a significant need for a simple means of tranferring prefabricated letters or characters to a "paste up" sheet for later photographing or printing. A dry rub-on transfer letter process is well known. However, these materials are supplied in sheets and the transfer must be made very carefully to produce carefully aligned and spaced images. Machines were later developed which prepared such letters on a continuous tape and this solved many of the aligment problems. An example of such machine is shown in PCT publication No. WO82/03600 and in U.S. Pat. Nos. 3,912,064 and 4,243,333. Since the paste up may be used in an enlargement with high resolution printing, the spacing of the characters must be accurately controlled. Even small errors in spacing or kerning would be very apparent upon enlargement.
Prior art devices provide mechanical means for advancing the tape, such as U.S. Pat. Nos. 1,800,195 and 3,768,619. Unfortuntely, wear of the mechanism over time will cause slight changes in the forward incrementation of the tape and accuracy will not be maintained. The present invention overcomes this problem by providing a simple electromechanical system which uses a minimum of precision parts yet maintains constant tape feed incrementation even after the replacement of parts.
Furthermore, it is also essential to have a reliable tape holding mechanism to insure that the characters will be perfectly aligned in their vertical orientation. In addition, this alignment means must be capable of releasing the tape rapidly so that an automated printing mechanism can produce a stream of characters without impediment. The present invention also provides for such a tape guiding mechanism particularly well suited to automated printing machines.